RE:who`s wearing the shorts nowThe same scenario can happen, albeit not quite as bad when buying LONG in a margin account. You only have to put up 25% of the value of a stock to purchase it. The rest is loaned to you. So if you put $10,000 cash in a margin account and bought $10,000 worth of shares on the margin you'd only have to put up $2,500. You would have $7,500 worth of "buying power" left to purchase other stocks. If all the stocks in your portfolio begin to fall you are OK as long as the buying power remains in the + position. As the stocks continue to drop your buying power will become zero. Should the value of the stocks drop enough that your have negative buying power, you face a margin call. You ususally have 3 days to satisfy the call by depositing more cash. HOWEVER, if the value of your assets drop low enough such that your total buying power and assets fall below the total $10,000 value, you are now "under equity", and the broker will sell your assets and demand the difference in cash or other equity. They can take your house away from you.